This proposal is a blinded, prospective, multi-institutional, phase 2 evaluation of differential light transmission scanning (diaphanography, transillumination, or spectroscopy). The study is designed to determine: 1) specificity and sensitivity by stage and size of breast cancer detected in a symptomatic, referred population; 2) transferability of the technology; and 3) relationship of the independent contributions for detection of blinded clinical examination, blinded mammography and blinded spectroscopy interpretations. After adequate training and testing of all participants has been achieved, all observers will participate in a round-robin reading of all cases collected at each institution. The data base, including all follow up data, will be maintained at the University of Cincinnati Medical Center Computer Center. No correlative information will be released to the participating investigators until the conclusion of the study. From these data, the supplementary or complementary role of Spectrascanning in the diagnostic evaluation of patients with suspected breast cancer should be possible. If the test shows promise in detecting minimal breast cancers, further evaluation of the modality as a screening tool will be feasible. The imaging equipment is currently available at each institution. It will be necessary to examine at least 6000 patients for this study to accrue sufficient stage 1 and stage 2 cancers, and provide a reasonable sampling of minimal breast cancers. This will cost $49.00 per person examined exclusive of indirect costs. If the modality can replace or reduce the reliance on ionizing radiation for earlier detection, the potential health benefits are obvious. Further, by defining the limitations and benefits of the method, more appropriate and cost effective clinical use can be made of it.